linux-kernel - [RFC net-next v3 5/7] net: devmem: pull out dma_dev out of net_devmem_bind

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Message-ID: <20250815110401.2254214-7-dtatulea@nvidia.com>
Date: Fri, 15 Aug 2025 14:03:46 +0300
From: Dragos Tatulea <dtatulea@...dia.com>
To: <almasrymina@...gle.com>, <asml.silence@...il.com>, "David S. Miller"
	<davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
	<kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman
	<horms@...nel.org>
CC: Dragos Tatulea <dtatulea@...dia.com>, <cratiu@...dia.com>,
	<tariqt@...dia.com>, <parav@...dia.com>, Christoph Hellwig
	<hch@...radead.org>, <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [RFC net-next v3 5/7] net: devmem: pull out dma_dev out of net_devmem_bind_dmabuf

Fetch the DMA device before calling net_devmem_bind_dmabuf()
and pass it on as a parameter.

This is needed for an upcoming change which will read the
DMA device per queue.

This patch has no functional changes.

Signed-off-by: Dragos Tatulea <dtatulea@...dia.com>
---
 net/core/devmem.c      | 14 ++++++--------
 net/core/devmem.h      |  2 ++
 net/core/netdev-genl.c | 12 ++++++++----
 3 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/net/core/devmem.c b/net/core/devmem.c
index d66cb0a63bd6..c7ca16c9fc04 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -176,30 +176,28 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 
 struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev,
+		       struct device *dma_dev,
 		       enum dma_data_direction direction,
 		       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
 		       struct netlink_ext_ack *extack)
 {
 	struct net_devmem_dmabuf_binding *binding;
 	static u32 id_alloc_next;
-	struct device *dma_dev;
 	struct scatterlist *sg;
 	struct dma_buf *dmabuf;
 	unsigned int sg_idx, i;
 	unsigned long virtual;
 	int err;
 
-	dmabuf = dma_buf_get(dmabuf_fd);
-	if (IS_ERR(dmabuf))
-		return ERR_CAST(dmabuf);
-
-	dma_dev = netdev_queue_get_dma_dev(dev, 0);
 	if (!dma_dev) {
-		err = -EOPNOTSUPP;
 		NL_SET_ERR_MSG(extack, "Device doesn't support dma");
-		goto err_put_dmabuf;
+		return ERR_PTR(-EOPNOTSUPP);
 	}
 
+	dmabuf = dma_buf_get(dmabuf_fd);
+	if (IS_ERR(dmabuf))
+		return ERR_CAST(dmabuf);
+
 	binding = kzalloc_node(sizeof(*binding), GFP_KERNEL,
 			       dev_to_node(&dev->dev));
 	if (!binding) {
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 41cd6e1c9141..101150d761af 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -85,6 +85,7 @@ struct dmabuf_genpool_chunk_owner {
 void __net_devmem_dmabuf_binding_free(struct work_struct *wq);
 struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev,
+		       struct device *dma_dev,
 		       enum dma_data_direction direction,
 		       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
 		       struct netlink_ext_ack *extack);
@@ -170,6 +171,7 @@ static inline void net_devmem_put_net_iov(struct net_iov *niov)
 
 static inline struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev,
+		       struct device *dma_dev,
 		       enum dma_data_direction direction,
 		       unsigned int dmabuf_fd,
 		       struct netdev_nl_sock *priv,
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 6314eb7bdf69..3e2d6aa6e060 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -876,6 +876,7 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 	u32 ifindex, dmabuf_fd, rxq_idx;
 	struct netdev_nl_sock *priv;
 	struct net_device *netdev;
+	struct device *dma_dev;
 	struct sk_buff *rsp;
 	struct nlattr *attr;
 	int rem, err = 0;
@@ -921,8 +922,9 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 		goto err_unlock;
 	}
 
-	binding = net_devmem_bind_dmabuf(netdev, DMA_FROM_DEVICE, dmabuf_fd,
-					 priv, info->extack);
+	dma_dev = netdev_queue_get_dma_dev(netdev, 0);
+	binding = net_devmem_bind_dmabuf(netdev, dma_dev, DMA_FROM_DEVICE,
+					 dmabuf_fd, priv, info->extack);
 	if (IS_ERR(binding)) {
 		err = PTR_ERR(binding);
 		goto err_unlock;
@@ -986,6 +988,7 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
 	struct net_devmem_dmabuf_binding *binding;
 	struct netdev_nl_sock *priv;
 	struct net_device *netdev;
+	struct device *dma_dev;
 	u32 ifindex, dmabuf_fd;
 	struct sk_buff *rsp;
 	int err = 0;
@@ -1032,8 +1035,9 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
 		goto err_unlock_netdev;
 	}
 
-	binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd, priv,
-					 info->extack);
+	dma_dev = netdev_queue_get_dma_dev(netdev, 0);
+	binding = net_devmem_bind_dmabuf(netdev, dma_dev, DMA_TO_DEVICE,
+					 dmabuf_fd, priv, info->extack);
 	if (IS_ERR(binding)) {
 		err = PTR_ERR(binding);
 		goto err_unlock_netdev;
-- 
2.50.1